The U.S. plans to draw down and store more than a billion tons of CO2 annually by 2050, more than one fifth of what it currently emits. For that to be possible, carbon removal would have to become one of the world’s largest industries in just a few decades, expanding by more than 40 percent each year. That’s far faster than most technologies develop—although it is comparable to the pace of solar panels and electric vehicles. “It’d be one of the biggest things humans have ever done,” says Gregory F. Nemet, a professor of public policy at the University of Wisconsin–Madison, who wrote a book called How Solar Energy Became Cheap. “One of the hardest things we’ve ever done. But not unprecedented.”